Support for the arc of a mobile x-ray device

A positioning apparatus for supporting a C-arm of a mobile x-ray apparatus, the C-arm being mounted on a mobile cart with a stand and including an inner rotatable C-arm portion and a rigid outer C-arm portion attached to the stand by a pivoting mounting structure such that the C-arm is able to be oriented in a horizontal position, the positioning apparatus comprising:

• a base capable of being positioned on a floor;
• a horizontal C-shaped top surface supported by the base and adapted to support the inner rotatable C-arm portion, a shape of the horizontal C-shaped top surface corresponding to a flat area of an underside of the inner rotatable C-arm portion;
• wherein
• the horizontal C-shaped top surface includes a friction reducer to reduce friction between the horizontal C-shaped top surface and the underside of the inner rotatable C-arm portion in a direction of a horizontal circular trajectory performed during a cone beam computed tomography acquisition sequence.